Abstract
M.Sc. (Botany)
Senescence of carnation flowers is accompanied by an
increase in the sensitivity of the petals to ethylene. It
appears that ethylene sensitivity during normal senescence
and under stress conditions is induced by the production of
short-chain saturated fatty acids ranging in chain-length
from C7-C10 during the early stages.
During pollination-induced senescence these acids are
synthesized in the styles as a result of wounding and
transported to the corolla where they induce an increase in
ethylene sensitivity of the petals to ethylene, causing an
advancement in the timing of the climacteric peak in
ethylene production. It appears that the cell membrane is
the site' of action for short-chain fatty acids in their
regulation of ethylene sensitivity in plant tissues. These
acids cause an increase "in the ability of the tissue to bind
ethylene by affecting the physical properties of the cell
membranes. Treatment with STS results in a suppression of
ethylene sensitivity by stabilizing the cell membranes,
thereby decreasing the ability of ethylene to bind to its
receptor sites in the cell membranes. Treatment with
short-chain fatty acids overrides this stabilizing effect to
a great extent by increasing the permeability of cellular
membranes and thus the sensitivity of the carnation petal
tissue to ethylene.